1. Field of the Invention
The present invention relates to an optical device such as a lens device or the like used in television image sensing, and an image sensing system using the optical device.
2. Related Background Art
As a lens device used in television image sensing or the like, a device shown in FIGS. 3 and 4 is known. In this lens device, a movable lens group (not shown) held in a housing 39 can be moved by rotating an operating ring 31 provided to the outer circumferential surface of a device main body 30 manually or by a motor, or a stop (not shown) can be adjusted.
A drive unit 32 provided near the housing 39 houses a motor 35 for motor-driving the operating ring 31, a control circuit (not shown), and the like, and a motor operating switch 33, which is operated by the user to operate the motor 35 to drive the movable lens group is provided on the outer surface of the drive unit 32.
This lens device has a clutch mechanism for connecting/disconnecting a driving power transmission path for transmitting the drive force of the motor 35 to the operating ring 31, as shown in FIG. 4.
More specifically, the clutch mechanism is made up of an idler gear 37 provided between an operating gear portion 34 formed on the operating gear 31 and an output gear 36 of the motor 35, and a clutch operating lever (not shown) which slides the idler gear 37 in the axial direction (longitudinal direction) of an idler shaft 38.
Upon motor driving, the clutch operating lever is operated to shift the idler gear 37 to mesh with both the operating gear portion 34 and output gear 36, thus connecting the drive force transmission path. Upon manual driving, the clutch operating lever is switched to shift the idler gear 37 to disengage from the output gear 36, thus disconnecting the drive force transmission path.
However, in the aforementioned lens device, the clutch operating lever must be operated to select the manual or motor driving mode of the operating ring. For this reason, operation is troublesome, and the manual and motor driving modes cannot be quickly switched, thus often failing to catch up with changes in image sensing situation.
Even when the drive force transmission path is connected, and while the movable lens group is motor-driven, the operating ring can be manually driven in terms of a structure. However, since a very large operating force is required due to the motor load, operation is not easy, and the motor is overloaded. Furthermore, when the movable lens group or the like is motor-driven via a camera control unit (CCU) placed at a position separated from this lens device and a camera to which that lens device is mounted, it is difficult for a person taking photographs who is near the camera to manually operate the operating ring preferentially.
It is, therefore, an object of the present invention to provide an optical device which is adopted quickly switch the motor-driven/manual state of a drive mechanism for driving a movable portion without requiring any special operation so as to avoid a problem such as overload of a motor when the movable portion is manually operated while the drive mechanism is set in the motor-driven state.
An aspect of the first invention of the present application that achieves the above object is characterized in that an optical device comprises:
an optical member that comprises the optical device;
an operating ring which can be rotated about an optical axis of the optical member and is used to drive the optical member;
a switching mechanism which transmits a drive force from a motor drive source to the operating ring, and can be switched between a state for motor-driving the optical member and a state for canceling motor driving of the optical member; and
control means for switching the switching mechanism between the state for motor-driving the optical member and the state for canceling motor driving of the optical member, and
the control means switches the switching mechanism to the state for canceling motor driving of the optical member on the basis of manual operation of the operating ring when the switching mechanism is set in the state for motor-driving the optical member.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a load state of the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a drive current value of the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a counterelectromotive force produced in the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a difference between a drive state of the optical member corresponding to a drive command, and an actually driven state of the optical member.
In a preferred aspect, the drive command is to command a drive position of the optical member, and the control means detects manual operation of the operating ring on the basis of a difference between the drive position command of the optical member, and an actually driven position.
In a preferred aspect, the drive command is to command a drive velocity of the optical member, and the control means detects manual operation of the operating ring on the basis of a difference between the drive velocity command of the optical member, and an actually driven velocity.
In a preferred aspect, the switching mechanism has a clutch mechanism for connecting/disconnecting drive force transmission between the operating ring and the motor drive source, and the control means switches the switching mechanism from the state for motor-driving the optical member to the state for canceling motor driving by switching the clutch mechanism from a connected state to a disconnected state.
In a preferred aspect, the optical member is a lens having a zoom function.
In a preferred aspect, the drive command of the optical member is input from operation means operated by a user.
In a preferred aspect, the drive command of the optical member is input from a control unit located at a position separated from the optical device.
In a preferred aspect, the drive command of the optical member is input from an image sensing device which is mounted on the optical device to be able to communicate therewith, and senses an image.
In a preferred aspect, the switching mechanism is driven by the motor drive source which operates in accordance with operation of motor operation means.
A second aspect of the invention of the present application that achieves the above object is characterized in that an image sensing system comprises:
an optical member that comprises an optical device;
an operating ring which can be rotated about an optical axis of the optical member and is used to drive the optical member;
a switching mechanism which transmits a drive force from a motor drive source to the operating ring, and can be switched between a state for motor-driving the optical member and a state for canceling motor driving of the optical member;
control means for switching the switching mechanism between the state for motor-driving the optical member and the state for canceling motor driving of the optical member; and
an image sensing device which is mounted on the optical device to be able to communicate therewith, and senses an image, and
the control means switches the switching mechanism to the state for canceling motor driving of the optical member on the basis of manual operation of the operating ring when the switching mechanism is set in the state for motor-driving the optical member.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a load state of the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a counterelectromotive force produced in the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a difference between a drive state of the optical member corresponding to a drive command, and an actually driven state of the optical member.
In a preferred aspect, the switching mechanism has a clutch mechanism for connecting/disconnecting drive force transmission between the operating ring and the motor drive source, and the control means switches the switching mechanism from the state for motor-driving the optical member to the state for canceling motor driving by switching the clutch mechanism from a connected state to a disconnected state.